Double, Metachronous Thyroid Metastases of Colon Cancer

A case of double, metachronous thyroid metastases of colon cancer with a long survival is described. A 52-year-old woman was referred to our Institute in October 2003 for a nodule in the left lobe of the thyroid _ gland. She had a history of left colon adenocarcinoma diagnosed elsewhere in August 1999 and treated with preoperative chemotherapy (Folfox for only one cycle, due to toxicity), surgery (anterior colon-rectum resection) and postoperative radiation. The tumor was classified as pT3pNIMO. In July 2002 the patient had undergone in lateral thoracotomy a right lung metastasectomy of colon adenocarcinoma and a regional lymphadenectomy. Follow-up was unremarkable until October 2003, when a PET scan visualized a nodule of 2 em in diameter in the left lobe of the thyroid. A tru-cut biopsy was performed, which resulted in a diagnosis of metastasis of colon adenocarcinoma involving the thyroid parenchyma. Immunohistochemical analysis showed expression of cytokeratin 20 and 7 in the colon adenocarcinoma metastasis and no expression of thyroglobulin or thyroid transcription factor 1. In 1 month the nodule reached a diameter of 4 x 3 em, partially involving the thyroid isthmus. No laterocervical nodes were palpable and larynx motility was conserved. A hemithyroidectomy plus isthmectomy was then performed. The histological diagnosis on the surgical specimen confirmed the biopsy findings: moderately differentiated colon-type adenocarcinoma with necrotic foci and vascular invasion (Figure 1). Two regional nodes were tumor negative. Immunohistochemistry was performed to test the immunoreactivity of the tumor for EGFR, CD117 and p185 for possible treatment with gefitinib, imatinib or Herceptin, respectively. While CD117 and the Herceptest were negative, EGFR in the tumor came up positive. In Eebruary 2004 a mobile, 2.5 x 2 em nodule appeared in the left prethyroid soft tissue. There were no palpable laterocervical lymph nodes. The nodule was excised. The histological diagnosis was a metastasis of colon adenocarcinoma in the left prethyroid fibromuscular tissue without any evidence of lymph node involvement. Postoperative radiation was performed with a total dose of 60 Gy. In June 2004 multiple bilateral lung metastases were detected and treated with the tyrosine kinase inhibitor gefitinib and the anti angiogenic bevacizumab. this treatment resulted in a period of clinical wellbeing with a radiological partial response. In May 2005 a nodule in the superior pole of the right lobe of the thyroid was found. A tru-cut biopsy documented a metastasis of colon adenocarcinoma. In view of the good clinical condition of the patient with longlasting stability of the lung metastases, she underwent elsewhere a right hemithyroidectomy along with resection of the sternothyroid muscle to obtain local surgical radicality. Thyroid hormone replacement therapy was initiated. The patient is currently in good general condition and undergoing regular clinical and radiological follow-up 30 months after her first surgery for thyroid metastases.